UCLA Imaging Study Shows Changes in Brain Function Even 10 Years After Cancer Patients Undergo Chemotherapy

Cancer survivors, take note. The mental fog and forgetfulness of "chemo brain" are no figment of your imagination.

A new UCLA study shows that chemotherapy causes changes to the brain's metabolism and blood flow that can linger at least 10 years after treatment. Reported Oct. 5 in the online edition of the journal Breast Cancer Research and Treatment, the findings may help to explain the disrupted thought processes and confusion that plague many chemotherapy patients.

"People with 'chemo brain' often can't focus, remember things or multitask the way they did before chemotherapy," explained Dr. Daniel Silverman, head of neuronuclear imaging and associate professor of molecular and medical pharmacology at the David Geffen School of Medicine at UCLA. "Our study demonstrates for the first time that patients suffering from these cognitive symptoms have specific alterations in brain metabolism."

Silverman and his colleagues used positron emission tomography (PET) to scan the brains of 21 women who had undergone surgery to remove breast tumors five to 10 years earlier. Sixteen of them had been treated with chemotherapy regimens near the time of their surgeries to reduce the risk of cancer recurrence.

The team compared PET images evaluating the chemotherapy patients' brain function to PET scans from five breast-cancer patients who underwent surgery only, and 13 control subjects who did not have breast cancer or chemotherapy.

As the women performed a series of short-term memory exercises, the UCLA team measured blood flow to their brains. The researchers also ran a scan of the patients' resting brain metabolism after the women finished the exercises.

"The PET scans show a link between chemo-brain symptoms and lower metabolism in a key region of the frontal cortex," explained Silverman. "We found that the lower the patient's resting brain metabolism rate was, the more difficulty she had performing the memory test."

The scans revealed that blood flow to the frontal cortex and cerebellum spiked as the chemotherapy patients performed the memory tests, indicating a rapid jump in these brain regions' activity level.

"The same area of the frontal lobe that showed lower resting metabolism displayed a substantial leap in activity when the patients were performing the memory exercise," said Silverman. "In effect, these women's brains were working harder than the control subjects' to recall the same information."

Finally, the researchers discovered that women who underwent hormonal therapy in addition to chemotherapy displayed changes to their basal ganglia, a part of the brain that works to bridge thought and action. On average, these women showed an 8 percent drop in resting metabolism in this brain region.

"Chemotherapy used to be prescribed primarily to treat metastatic disease," observed Silverman. "Now it's common for doctors to administer chemotherapy to patients near the time of surgery to prevent metastasis. As many of these patients become long-term survivors, doctors are recognizing lasting side-effects of chemotherapy, and, in particular, the kind of chemo-brain symptoms we are studying."

"Our findings suggest that PET scans could be used to monitor the effects of chemotherapy on brain metabolism," he added. "The approach could be easily added to current whole-body PET or PET/CT scans already being used to monitor patients for tumor response to therapy."

Although chemo brain is an acknowledged phenomenon, doctors don't know what mechanisms cause it. More studies are needed to uncover how the damage occurs and whether modification of chemotherapy drugs could prevent it.

The National Cancer Institute recently awarded a five-year grant to oncologist Dr. Patricia Ganz, who is organizing a long-term study on chemo brain of a larger group of breast-cancer survivors with Silverman and their colleagues at UCLA.

More than 211,000 new cases of breast cancer are diagnosed a year, making it the most common cancer in women. Experts estimate that at least 25 percent of chemotherapy patients are affected by chemo brain, and a recent study by the University of Minnesota reported an 82 percent rate.

Source: UCLA

Related stories:

Brain cancer study: Magnitude of post-vaccine immune response linked to clinical outcomes
Researchers conducting a clinical trial of a dendritic cell vaccine designed to fight malignant brain tumors called glioblastoma multiforme (GBM) have found a correlation between the "intensity" of a patient's immune response and clinical outcome, according to an article in the July 15 issue of the journal Cancer Research.
Weeding out the highs of medical marijuana
Research exploring new ways of exploiting the full medicinal uses of cannabis while avoiding unwanted side-effects will be presented to pharmacologists today (Tuesday, 15 July) by leading scientists attending the Federation of European Pharmacological Societies Congress, EPHAR 2008.
Cancer drug shows promise against graft vs. host disease
A new University of Michigan study in mice suggests that a drug recently approved to fight cancer tumors is also able to reduce the effects of graft-versus-host disease, a common and sometimes fatal complication for people who have had bone marrow transplants.
Nanomaterials Key to New Strategies for Blocking Metastasis
A new treatment strategy using targeted nanoparticles to block metastasis with anti-cancer drugs leads to good results using significantly lower doses of toxic chemotherapy, with less collateral damage to surrounding tissue, according to a collaborative team of researchers at the Center of Nanotechnology for Treatment, Understanding, and Monitoring of Cancer at the University of California, San Diego. In designing this system, the investigators, led by David Cheresh, Ph.D., have identified what may become a generic method for using nanotechnology to target metastasis.
Vaccine may double survival in patients with deadly brain tumors
A vaccine aimed at inducing immunity to the most common and deadly type of brain tumor may stave off recurrence and more than double survival in patients, according to a new study led by researchers in Duke’s Preston Robert Tisch Brain Tumor Center.
Chemotherapy might help cancer vaccines work
Chemotherapy given in conjunction with cancer vaccines may boost the immune system’s response, potentially improving the effectiveness of this promising type of cancer therapy, according to a study by researchers in the Duke Comprehensive Cancer Center.
Common virus may serve as target for vaccine in fight against deadly brain tumors
By targeting a common virus, doctors may be able to extend the lives of patients diagnosed with the most prevalent and deadly type of brain tumor, according to a study led by researchers in Duke’s Preston Robert Tisch Brain Tumor Center.
Chemotherapy causes delayed severe neural damage
A commonly used chemotherapy drug causes healthy brain cells to die off long after treatment has ended and may be one of the underlying biological causes of the cognitive side effects – or “chemo brain” – that many cancer patients experience. That is the conclusion of a study published today in the Journal of Biology.

News discussion:

Medicine & Health news